Quantum switches and quantum memories for matter-wave lattice solitons

We study the possibility of implementing a quantum switch and a quantum memory using matter-wave lattice solitons and making them interact with 'effective' potentials (barrier/well) corresponding to defects of the optical lattice. In the case of interaction with an 'effective' potential barrier, the bright lattice soliton experiences an abrupt transition from complete transmission to complete reflection ( quantum switch) for a critical height of the barrier. The trapping of the soliton in an 'effective' potential well and its release on demand, without losses, shows the feasibility of using the system as a quantum memory. The inclusion of defects as a way of controlling the interactions between two solitons is also reported.